<?php
function dump(...$a){
    foreach ($a as $v){
        echo print_r($v,true).PHP_EOL;
    }
}
$array = [
    "key1" => ['LaborCapacityCheck',5],
    "key2" => 1,
    "key3" => 0,
    "key4" => '',
    "key5" => null,
    "key6" => 'null',
];
foreach ($array as $k => $v){
    // 不用isset和empty判断key存在与否
    if(array_key_exists($k,$array)){
        dump($k.'在');
    }else{
        dump($k.'不在');
    }
}